A manufacturing procedure of a display panel comprises mainly three processing stages: array processing, cell processing and module processing, in which, the array processing is primarily responsible for providing an array substrate for the cell processing.
In particular, the array processing comprises a continuous cycle of four processes performed on a glass substrate, i.e., film forming, masking, exposing and etching, and ultimately a desired pattern of thin-film-transistor (TFT) array is fabricated on the glass substrate, thereby forming an array substrate. In the masking process, the glass substrate after being coated with a photosensitive material needs to be heated, for allowing the photosensitive material coated on the glass substrate to be partially-cured, so as to ensure the quality of exposure with ultraviolet light on the photosensitive material during subsequent exposing process. FIG. 1 shows a conventional heating apparatus for heating a glass substrate. The heating apparatus comprises: a heating chamber 1′ for receiving a glass substrate, and a heating unit 3′ provided at the bottom of the heating chamber 1′; and a plurality of supporting pins 4′ on the heating unit 3′ for supporting the glass substrate. FIG. 2 is an enlarged view of a supporting pin 4′. The glass substrate faces the heating unit 3′. Here, it should be noted that in order to see clearly the supporting pins 4′ inside the heating chamber 1′, the top (i.e., the cover 2′) of the heating chamber shown in FIG. 1 is in an opened state. In addition, the cover 2′ can be opened to facilitate maintenance of the device inside the heating chamber 1′, but in normal state (including a state of heating a glass substrate) the cover 2′ is in a closed state, so that the heating chamber 1′ forms an airtight space. The structure of such heating chamber is also applicable to the present disclosure.
The heating operation of the heating apparatus is as following. Firstly, a glass substrate is put into the heating chamber 1′ in such a way that the glass substrate faces the heating unit 3′ and is supported on the plurality of supporting pins 4′, and then the glass substrate is heated by the heating unit 3′. Such heating operation requires physical contact between the glass substrate and the supporting pins, and this will cause not only hard collision and friction on the substrate and thus result in damages to the substrate, but also a temperature difference between portions of the substrate in contact with the supporting pins 4′ and other portions, of the substrate so that the glass substrate is non-uniformly heated.